Route-switching system for railroad classification yard

ABSTRACT

A route-switching control system, for a railroad classification yard, in which each route command, upon entry into the system, is transferred downstream to individual storage units (one for each track switch in the yard and each capable of storing a single route command) as far as possible, depending upon prior entry of other route commands. The track switches of the yard are aligned in accordance with each route command as received. As each car or cut of cars enters a track switch, the storage unit for that track switch is cleared automatically and any route command pertaining to that track switch which may be waiting in an upstream storage unit is then entered in the storage unit. If a &#39;&#39;&#39;&#39;catchup&#39;&#39;&#39;&#39; occurs, with two separate cuts approaching each other too closely to be separated in subsequent yard operations, the route command for the cut catching up with a preceding cut is automatically cancelled; the system effectively notifies the operator of the occurrence of a catchup and identifies the track switch at which the catchup has occurred. An automatic alarm indicates the failure of any track switch to complete a throw or the recycling of any track switch.

United States Patent [72] Inventor Robert W. Convey Oakland, NJ. [2]] Appl. No. 840,688 [22] Filed July 10, 1969 [45] Patented Aug. 10, 1971 [73] Assignee Abe: Corporation New York, N.Y.

[54] ROUTE-SWITCHING SYSTEM FOR RAILROAD CLASSIFICATION YARD l3 Clahm, 9 Drawing Pb.

[52] U.S.Cl ..246/182AA [51] B011 17/00 [50] Field otSearch 246/41 A, 182 A, 240, 242 R, 134; 104/26 [56] References Cited UNITED STATES PATENTS 1,976,822 10/1934 Young 246/240 X 2,700,728 1/l955 Brixner etal. ....246/182 AA UX 2,707,230 4/1955 Beltman et al 246/240 3,307,031 2/1967 Frielinghaus et al.... 246/134 X $37 l-u [:U' L 39 57-- 536 WLl-u Primary ExaminerArthur L. La Point Assistant Examiner-George H. Libman AuomeyKinzer, Dorn and Zickert ABSTRACT: A route-switching control system, for a railroad classification yard, in which each route command, upon entry into the system, is transferred downstream to individual storage units (one for each track switch in the yard and each capable of storing a single route command) as far as possible, depending upon prior entry of other route commands. The track switches of the yard are aligned in accordance with each route command as received. As each car or cut of cars enters a track switch, the storage unitfor that track switch is cleared automatically and any route command pertaining to that track switch which may be waiting in an upstream storage unit is then entered in the storage unit. If a catchup occurs, with two separate cuts approaching each other too closely to be separated in subsequent yard operations, the route command for the cut catching up with a preceding cut is automatically cancelled; the system effectively notifies the operator of the occurrence of a catchup and identifies the track switch at which the catchup has occurred. An automatic alarm indicates the failure of any track switch to complete a throw or the recycling of any track switch.

6-7 WL6-7 a] alj 5 1 Maw 31 wts-e fig .n xu tnggl j ggufi WLIO-u 6- =0 8... jU Q E 32 10- as n e a: TRACK sececrons fie KW-$6 me ijngmja m lg E] m 56 34' ts-te El E] m El b E E1 3351752 EIIEEIE ROUTE-SWITCHING SYSTEM FOR RAILROAD CLASSIFICATION YARD BACKGROUND OF THE INVENTION In railroad classification yards, and particularly in large yards having a substantial number of individual classification tracks, automatic route-switching control equipment is often employed to actuate the track switches in the yard and to control the passage of individual cars or cuts of cars through the yard. In the specification and in the appended claims, either a single car or a cut of cars is designated by the general term vehicle. In a yard of this kind, the track switches employed to divert vehicles along the many different routes leading to their final destination tracks are all electrically actuated b the route-switching equipment, although hydraulic, pneumatic, or mechanical switch machines may provide the motive power to throw the track switches. For effective operation, the routeswitching system must be provided continuously with information about the position of various vehicles moving through the yard. This is accomplished by track occupancy circuits associated with the various track switches, and occasionally, with long stretches of track between switches.

In one automatic route-switching system for railroad classification yards, a series of route commands are first recorded at a main control unit by a yard operator. As each vehicle passes through the first track switch at the upper or hump" end of the yard, the route information for that vehicle is transferred, in the route-switching control system, to a separate control unit that is associated with the next track switch downstream in the yard. When the vehicle clears the downstream switch, the route information is again transferred on to another control unit associated with the next downstream track switch. This procedure is followed until the final track switch leading to the destination for the vehicle is cleared. Thus, the transfer of information within this route switching system is sequential in nature, and information regarding each vehicle is applied to that part of the control system associated with a given track switch only when the vehicle approaches that track switch.

Another and often more advantageous route switching system, disclosed in the copending application of Robert B. McCune and Rosser L. Wilson, Ser. No. 667,504, filed Sept. 13, 1967, now U. S. Pat. No. 3,480,773 issued Nov. 25, 1969, comprises a main control unit that affords storage means for recording a number of complete route commands identifying complete individual routes to be transversely by the vehicles with readout means for reading out the stored route commands in sequence. In that system, a plurality of modular control units, one for each track switch, are utilized to control operation of each track switch in accordance with a partial route command relating to that switch and in accordance with the traffic conditions on a section of track encompassing the controlled switch and the immediately preceding track switch. Each of these control units affords local storage for recording several partial route commands relating to operation of its track switch. The transmission system simultaneously transmits partial route commands from the main control unit to all of the modular units affected by a given complete route command. In some installations this arrangement reduces the total storage capacity for the system, as compared with the older sequential system described above. The simultaneous transmission of route information down through the system also makes it possible to have the track switches set to a desired condition well in advance of each cut.

With either of the foregoing systems, however, the required storage capacity for route command information tends to be relatively large, particularly in large classification yards. The automatic route switching systems previously employed have also presented a number of operating problems. For example, in operation of the yard a given vehicle may accelerate more rapidly than anticipated, closing in on and sometimes even physically engaging a preceding vehicle having more sluggish rolling characteristics. An occurrence of this kind, even when physical contact is not made, is referred to as a catchup." In general, previously known automatic route control systems have not provided adequate warning of catchups and have not been readily adaptable to correction of previously stored route command information when a catchup occurs. In fact, in many systems it is possible for a catchup to occur early during a days operation and to go undetected, after which every vehicle sent through the classification yard is passed to the wrong destination track and the entire days operation for the yard is wasted.

Another difficulty presented in the operation of classification yards having automatic route-switching systems arises when a track switch fails to throw to the proper position, in a given operation. This may occur due to a blockage in the switch machine or to some other failure in the switch mechanism itself. If the switch hangs up in an intermediate position, this can result in a derailment or in a wreck within the yard. Even if there is no derailment or wreck, it may result in the transfer of vehicles to incorrect destination tracks with a consequent necessity for checking the destination tracks to determine whether the proper vehicles have been routed thereto.

SUMMARY OF THE INVENTION It is a principal object of the present invention, therefore, to afford a new and improved route-switching system for a railroad classification yard having minimum storage requirements for route command information and readily adaptable to construction with all solid state components. A related object of the invention is to afford a new and improved modular routeswitching control system for a classification yard that is easy to service and that is economical in construction.

Another object of the invention is to provide a new and improved route-switching control system for a railroad classification yard which afiords combined series-parallel handling of route command data; that is, the system transfers route command information downstream as soon as it is recorded in the system, but only far enough to reach the last previously recorded route command. Thus, the data storage units of the invention are never required to store more than one route command while affording, to a large extent, the timing and other advantages of a parallel transmission system.

Another important object of the invention is to provide a new and improved route-switching control system for a railroad classification yard in which each catchup causes an automatic cancellation of the route command for the vehicle catching up with a preceding vehicle, preserving the integrity of previously recorded route commands for subsequent vehicles. A related object of the invention is to provide a route switching control system which automatically notifies the yard operator of the occurrence of a catchup and informs him as to the track switch at which the catchup has occurred.

An additional object of the invention is to provide a new and improved route-switching control system that affords an automatic alarm whenever a track switch fails to complete a throw or recycles, with the alarm occurring in adequate time to allow the yard operator to take corrective action to prevent a derailment or other mishap in the yard.

Accordingly, the invention relates to a new and improved electrical control system for route switching in a railroad clas-- sification yard of the kind including a plurality of track switches interconnected by tracks in a given pattern for diverting vehicles along a series of routes diverging from a first track switch to a given number of different destination tracks. A control system constructed in accordance with the invention comprises a corresponding plurality of track switch control units, one for each track switch, each including a storage unit having a storage capacity sufficient to store a single route command that is encoded in accordance with a given destination code and that identifies a route through the track switch with which the storage unit is associated and through all other downstream track switches that must be traversed to reach a given destination. The system further comprises a limited number of preliminary storage units each having a storage capacity sufficient to store a complete route command for any destination in the yard. The track switch control units are interconnected with each other in a pattern corresponding to the pattern of tracks in the classification yard and the preliminary storage units are interconnected in a series, with the last storage unit in that series being the first of the track switch control storage units. Encoding means are provided for entering complete route commands in the first preliminary storage unit of the series. The system further comprises clearing means for automatically clearing each track switch control storage unit each time a vehicle traverses the track switch with which it is associated. The interconnections between the storage units are such that whenever a given storage unit is cleared, any route command pertaining thereto that has previously been stored in an adjacent upstream storage unit is automatically entered into the cleared storage unit.

In accordance with another aspect of the invention, the system is provided with track occupancy detection means, connected to each control unit, for monitoring the positions of vehicles moving through the classification yard and for supplying position signals to the control units. Each control unit is provided with a catchup control, responsive to the position signals, for clearing the preceding track switch storage unit of any route command stored therein whenever the position signals indicate the occurrence of a catchup. The preferred embodiment of the route-switching system also provides an automatic alarm that is operated promptly upon the failure of any track switch to complete a throwing operation, or upon the recycling of a track switch or the occurrence of any other condition in which the track switch fails to reach a desired position, the warning being presented immediately upon occurrence of the undesired track switch operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an operators control console for an automatic route-switching control system constructed in accordance with one embodiment of the present invention, illustrating the track layout for a classification yard of moderate size;

FIG. 2 is a general block diagram of an automatic routeswitching control system constructed in accordance with one embodiment of the present invention;

FIG. 3 is a detailed schematic diagram of the encoding matrix at the input end of the route-switching system of FIG.

FIG. 4 is a schematic diagram of the first two storage units in the automatic route switching system of FIG. 2;

FIG. 5 is a schematic diagram of the storage units for two track switch control units in the route-switching system of FIG. 2;

FIG. 6 is a timing diagram illustrating the occurrence of certain clock signals employed in the operation of the storage units of FIGS. 4 and 5;

FIG. 7 is a schematic diagram of the track circuits for one control unit in the automatic route-switching system of FIG. 2; and

FIGS. 8 and 9 are timing charts illustrating operation of the catchup circuit in the apparatus of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Description FIGS. 1 and 2 The general construction and operation of one embodiment of the automatic route-switching control system of the present invention can best be understood by reference to FIGS. 1 and 2. FIG. 1 is a plan view of an operators control console from which the system is actuated in ordinary operation. Console 20 includes an outline representation of the railroad classystem. This classification yard includes a given number of destination tracks 1 through 16 to which individual railroad vehicles are directed after entering the classification yard along an entrance track 21, sometimes referred to as the hump track, in the direction indicated by the arrow 19.

Within the classification yard there are a series of track switches that control the movement of the vehicles traversing the yard toward the destination tracks 1 through 16. These track switches, as represented on the console 20 in FIG. 1, are numbered in accordance with the destination tracks that they serve. Thus, the first track switch 1-16, through which all vehicles pass in moving toward any of the destination tracks 1 through 16, branches into two intermediate tracks 22 and 23. Track 22 leads into a track switch 1-11 that in turn branches to intermediate tracks 24 and 25. Track 24 connects with a track switch 1-2 that leads to destination tracks 1 and 2. Intermediate track 27 leads to a track switch 3-5 which branches into destination track 3 and an intennediate track 28. Intermediate track 28 leads to a track switch 4-5 which branches to the destination tracks 4 and 5.

The intermediate track 25 extends to a track switch 6-11 that leads to two intermediate tracks 29 and 30. Track 29 extends into a track switch 6-7 that branches to the destination tracks 6 and 7. Track 30 extends to a track switch 8-11 that branches to two intermediate tracks 31 and 32. Intermediate track 31 leads to a track switch 8-9 that serves destination tracks 8 and 9. Intermediate track 32 terminates at a track switch 10-11 that leads to destination tracks 10 and 1 1.

Intermediate track 23 terminates at a track switch 12-16 that branches to two intermediate tracks 33 and 34. Intermediate track 34 leads to a track switch 15-16 serving destination tracks 15 and 16. Intermediate track 33 extends to a track switch 12-14 that leads to a destination track 14 and to an intermediate track 35. Intermediate track 35 terminates at a track switch 12-13 that serves destination tracks 12 and 13.

Each of the track switches shown on the operator's console 20 is provided with a three-position manual-operating switch as exemplified by the switch WLl-16 for track switch 1-16. Each of these switches has an automatic position, with the switch-operating arm thrown completely to the left. Each of the manual-operating switches has a center open position. And each of the manual-operating switches, such as switch WL1-16, has a momentary contact position, with the switch operating member thrown to the extreme right, that is used to throw the track switch 1-16 with which it is associated. Each of the manual-operating switches is identified by a reference numeral corresponding to that of the track switch with which it is associated but having the prefix WI.."

On the operatorsconsole 20, as illustrated in FIG. 1, there is an indicator lamp located at the left-hand or entrance end of each of the track switches 1-16 through 15-16. These indicator lamps are typified by the lamp 36 at the entrance end of the initial track switch 1-16. Lamp 36 is energized whenever the occupancy detector for track switch 1-16 determines that a vehicle is present in the track section encompassing that track switch. The similarly positioned indicator lamps for each of the remaining track switches are each electrically connected to the route-switching control system, as described more fully hereinafter, to afford a similar indication for occupancy of the track switches with which they are associated.

Track switch 1-16, as represented on operator's console 20, also has two indicator lamps 37 and 38 located at its outlets to intermediate tracks 22 and 23, respectively. Indicator lamps 37 and 38 serve several purposes in indicating to the operator the position and operational status of track switch 1-16, as described more fully hereinafter. A similar pair of outlet-track indicator lamps is provided for each of the remaining track switches represented on the operators console.

There is another indicator lamp 39 located in the representation of the hump track 21 at the extreme left of the classification yard diagram of operators console 20. Lamp 39 is energized whenever any one of the manual control switches sification yard that is controlled by the route-switching WL1-16 through WL15-16 has been thrown to any position other than its left-hand automatic position. Thus, lamp 39 signals to the operator that some part of the automatic routeswitching control system is not in condition for automatic route selection and control and correction may be required before normal operation can proceed.

Console 20 further comprises a series of individual track selectors 40, located in the lower left-hand portion of the console as seen in FIG. 1. Each of the track selectors 40 is an illuminated pushbutton switch. There are 16 track selectors 40, one for each destination track 1 through 16.

Immediately above the track selectors 40, on console 20, are a series of four route command indicators or windows 41 through 44. The route command indicators 41 through 44 alTord the operator a visual indication of particular route commands that have previously been entered into the system to control the movement of vehicles through the yard to selected destination tracks. Window 44 shows the route command that will be effective for the next cut entering the yard at switch 1-16. Windows 43, 42, and 41 in that order, identify the tracks to which successive vehicles will be directed. For the conditions illustrated in FIG. 1, the next vehicle entering the yard will be directed to destination track 6, after which successive vehicles will be routed to destination tracks 12, 16 and 3. Immediately below route command indicators 41-44 there are four pushbutton switches 51-54. These switches are employed to cancel previously stored route commands from the system as described more fully hereinafter.

There is one additional control element illustrated on console 20 as represented in FIG. 1. This is a pushbutton switch 56 that can be utilized by the yard operator to determine, instantaneously, the operating positions for all of the track switches 1-16 through -16.

FIG. 2 affords a general block diagram for the routeswitching control system actuated by console of FIG. 1. As shown therein, each of the selector keys 40 is electrically connected to an encoding matrix 60 having a plurality of output circuits which are all connected to a first preliminary storage unit 61. The four cancel switches 51 through 54 are all electrically connected to encoding matrix 60.

Storage unit 61 is provided with an output connection to a display coder circuit 71 that actuates the display device or window 41. Storage unit 61 is also provided with an output connection (actually a plurality of output circuits as described more fully hereinafter) to a second preliminary storage unit 62. A data feedback connection is provided from storage unit 62 to storage unit 61. Storage unit 62 has an output connection to a display coder 72 that actuates route command display 42.

There is a third preliminary storage unit 63 in the system illustrated in FIG. 2 that is connected to the preceding preliminary storage unit 62 and to a display coder 73. Storage unit 63 is in turn connected to a fourth storage unit RS l-16 that actuates a display coder 74 to control route command display 44. It is thus seen that the four storage units 61, 62, 63 and RSI-l6 determine the information that is shown in the route command display windows 41-44. These four preliminary storage units are all connected together in series; their operation is described in detail hereinafter.

Storage unit RSI-16, unlike the preceding preliminary storage units, is incorporated in and forms a part of a track switch control unit GUI-l6. The control unit, in addition to its internal storage unit RSI-16, comprises a switch control circuit YW1-l6 that has both input and output connections to the storage unit. Switch control circuit YW1-ll6 is electrically connected to the manual-operating switch WL1-l6 for the first track switch l-16 in the yard (see FIG. 1). Control unit CU1-l6 also includes a track occupancy detector for detecting the presence of any vehicle in the track section that includes track switch 1-16, as well as appropriate positionsensing switches for detecting the current position of track switch 1-16; these parts of the system are shown in FIG. 2 as track circuits TK1-16 electrically connected to the switch control circuit YW1-l6. It will be understood that the internal electrical connections for the components of control unit CU1-16 are greatly simplified in FIG. 2.

In the control system illustrated in FIG. 2, there is a control unit for each track switch in the yard, each control unit including a storage unit having a storage capacity sufiicient to store a route command that identifies a route through the particular track switch with which the control unit is associated and through all other track switches required to reach any destination downstream of that particular track switch. Furthermore, the control units of the system, starting with the control unit CUl-16, are all interconnected with each other in a pattern corresponding to the pattern of track connections between track switches in the classification yard. The storage unit RS1-16 of control unit CU1-l6 is common to the series of preliminary storage units 61,62 and 63 and to the track switch storage units.

Thus, control unit CU1-16 is connected to two downstream control units CUl-ll and CU12-l6 for track switches l-11 and 12-16 respectively. Within control unit CUl-ll, there is a route storage unit RS l-ll that is electrically connected to a switch control circuit YWl-ll. The switch control circuit is connected to the track circuits TKl-ll for track switch 1-11 and to the manual-operating switch WLl-ll for track switch 1-11. The storage unit RSI-11 has input and output connections to the preceding storage unit'RS1-16. There is also an electrical connection from the switch control circuit YW l-ll back to the storage unit RSI-16 in the preceding stage of the route-switching system.

The connections for the control unit CUl2-l6 are essentially similar. This control unit comprises an internal storage unit RS12-16 that is electrically connected to a switch control circuit YW12-16, the storage unit and the switch control circuit both being connected back to the storage unit RS1-16 in the preceding stage of the system. Within control unit 12-16, themanual-operating switch WLll2-l6 and the local track circuits TI(1216, both associated with track switch 12-16, are electrically connected to the switch control circuit YW12-16.

The next stage of the system, downstream from control unit CUl-ll, comprises two control units CUl-S and CU6-1 l for track switches 1-5 and 6-11 respectively. Each of these two control units includes its own internal route command storage unit, a switch control circuit, the local track circuit and a manual-operating switch. In each instance, the storage unit and the switch control circuit, in addition to their internal interconnections, are connected back to the storage unit RSI-l1 in the preceding stage.

Downstream of control unit CU12-16, there are two additional control units CUl2-14 and CU15-16 for track switches 12-14 and 15-16, respectively. Control units CU12-14 and CUl5-16 correspond to those described above; each includes a route command storage unit, switch control circuit, and local track circuits, and a manual-operating switch. Control unit CUl5-l6 does not afford any further connections to a downstream control unit because its associated track switch I5-l6 is a terminal track switch serving only two destination tracks.

Where there are long stretches of intermediate track between track switches, it may be desirable to provide additional storage capacity within the system to store route commands for more than one vehicle transversing the long inter mediate track. If it is assumed that track 34 (FIG. 1) constitutes a long intermediate track of this kind, additional storage for one or more additional route commands pertaining to trafiic between switches 12-16 and 15-16 may be incorporated in the system. This is accomplished by an intermediate storage unit 75 (FIG. 2) electrically connected between the control units CU12-16 and CU15-16. In some classification yards there may be no necessity for an intermediate storage unit of this kind; in others, they may be desirable for relatively long intermediate storage tracks such as tracks 23, 24, 26 and 29, as well as track 34.

To enter route command information into the system, the operator uses the track selector switches 40 (FIG. 1). Thus, if

it is assumed that the yard was not in operation prior to entry of the route commands shown in displays 41-44, the first action taken by the operator would be to actuate the track selector 40 for destination track 6. On operation of this track selector, an electrical circuit is completed in encoding matrix 60 (FIG. 2) to enter a complete route command, encoded in accordance with the destination track 6, in the first preliminary storage unit 61 of the system. This first route command is not retained for any substantial length of time in storage unit 61, since the succeeding preliminary storage unit 62 has no route command recorded therein. Thus, the initial route command pertaining to destination track 6 is immediately transferred to the next preliminary storage unit 62 and then to the succeeding preliminary storage unit 63 and finally to the first of the track switch storage units, storage unit RSI-16 in control unit CU1-16. As the route command passes through storage units 61, 62 and 63, those storage units are automatically cleared.

Once the route command has reached storage unit RSI-16, it is retained in that storage unit until a vehicle passes through the associated track switch 1-16. As long as no vehicle passes through track switch 1-16, the route command is continuously displayed at window 44. Moreover, the stored route command in unit RSI-16 actuates switch control circuit YW1-16 to maintain track switch 1-16 in its nonnal position, routing any incoming vehicle to intermediate track 22. If track switch 1-16 actuates the track switch and throws it to its normal position.

The initial route command pertaining to destination track 6, starting with a cleared system as hypothesized above, does not stop at storage unit RSI-16. Instead, the pertinent part of the route command, although retained in storage unit RSI-16, is also recorded in storage unit RSI-l l of control unit CUl-ll for track switch 1-11, the next track switch en route to destination track 6. The route command, when stored in route storage unit RSI-l1, actuates switch control circuit YW 1-11 to place track switch YWl-ll in its reverse" position to route any incoming vehicles to intermediate track 25.

The pertinent portions of the route command for destination track 6 are further transferred downstream to storage unit RS-ll in control unit CU6-11, since track switch 6-11 must be traversed by any vehicle destined for track 6. The route command information is stored in storage unit RS6-1l and is employed to actuate switch control circuit YW6-11 to throw track switch 6-11 to its normal position (or to maintain the track switch in its normal position if it is already there). The necessary route command information is also transferred downstream to that portion of the control system pertaining to track switch 6-7, the last track switch on the route to destination track 6.

The next route command is entered in the system by the operator actuating the track selector 40 relating to the next desired destination track, track 12. As before, actuation of the track selector by the console operator causes the encoding matrix 60 to produce a coded output signal that records the new destination track in preliminary storage unit 61. As before, this route command is transferred downstream of the preliminary storage units until it reaches preliminary storage unit 63. But this route command is not transmitted beyond storage unit 63 because a route command is already stored in the succeeding storage unit RSI-l6 and no vehicle has passed through the system to clear storage unit RSI-16. Thus, the second route command, for the time being, remains stored in preliminary storage unit 63 and is displayed for the use of the operator by the display coder 73 and display device 43.

The third and fourth route commands, pertaining to destination tracks 16 and 3, are entered in sequence, by the operator, in the manner described above. The route command pertaining to track 16 is stored in preliminary storage unit 62; it cannot be sent further downstream because a route command has already been stored in the succeeding storage unit 63. By the same token, the command pertaining to destination track 3, the fourth command entered in the system, gets no farther than preliminary storage unit 61.

As soon as the first vehicle moves into the classification yard and enters track switch 1-16, its presence there is detected by the occupancy detector of track circuits TK1-16. That is, the track occupancy detection means in track circuits TKl-16 supplies a vehicle position signal to switch control circuit YW1-16. This signal is also supplied to storage unit RSI-l6 to clear the track switch storage unit. When storage unit RSI-l6 has been cleared, it enables transfer of the route command from the preceding storage unit 63, and the route command pertaining to the next vehicle, which is destined for track 12, is then transferred into storage unit RSI-16 from storage unit 63. I

When the first vehicle clears track switch l-16, a further position signal is developed by track circuit TK1-16. The position signal, applied to switch control circuit YWl-16, enables the switch control circuit to utilize the new route command now stored in storage unit RSI-16 to actuate track switch 1-16 to its reverse position as required for the next vehicle, which is to be routed to destination track 12. It is thus seen that the route command information is transferred into the storage unit RSI-16 for track switch 1-16 as soon as the storage unit has been cleared of a prior route command by entry of a vehicle into the track switch, and is used to throw the track switch as soon as the vehicle clears the track switch on its way down the yard.

The foregoing operation of control unit CU1-16 is repeated for each of the succeeding control units for the track switches that route the first vehicle to destination track 6. Thus, when the first vehicle enters track switch l-ll, its presence is detected and is used to clear storage unit RSI-11 of the previously recorded route command. Since the next route command pertains to a track that does not utilize track switch 1-11, storage unit RSI-l1 remains in cleared condition until a route command passes down through the system that requires use of track switch 1-11. Switch control circuit YW l-ll does not actuate track switch 1-11 to a new operating condition until the first vehicle clears the track switch and a new route command is available. The track switch cannot be changed in its operating position, once a vehicle has entered it, until after the vehicle clears the switch.

As soon as the first route command has been cleared from storage unit RSI-16 and the succeeding route command has been entered therein from storage unit 63, storage unit 63 is automatically cleared and the next route command is transferred thereto from storage unit 62. This clears storage unit 62 and automatically initiates a transfer of the next route command from the storage unit 61. This in turn clears storage unit 61 and conditions the system for the reception of an additional route command when desired by the operator. Thus, as each vehicle passes through switch l-16, the route commandfor switch 1-16 drops out and all route commands previously stored in the preliminary storage units advance one stage.

Whenever the first display window 41 is blank, additional route commands can be entered by the yard operator, up to a maximum number sufficient to fill all of the preliminary storage units including storage unit RSI-16.

After entry of a given route command, the operator may discover that an error has been made. For example, he may have actuated the wrong track selector or he may have entered a route command that would send a vehicle to a destination track that is already full. To cancel that route command, it is only necessary for the yard operator to actuate the particular cancel switch associated with the display device in which the erroneous route command is shown. Thus, if the route command pertaining to destination track 12 that appears in window 43 is in error, the operator actuates cancel switch 53. This cancels the route command presently appearing in window 43 and all of the route commands in the preceding stages of the system. Corrected or additional route commands may be entered by the operator immediately after the cancellation operation.

As noted above, the lamp 39 at the left-hand end of the incoming track 21 (FIG. 1) is illuminated whenever one or more of the manual-operating switches WL1-16 through WL-16 is not in its automatic position. With this warning, the yard operator can easily detect which particular manual-operating switch is out of its automatic position by checking the positions of the switch control levers. If it is necessary to leave one of the manual-operating switches in its open position, all other track switches downstream from that position must be actuated manually to route any vehicles in that direction.

The two position lamps 37 and 38 for track switch 1-16 give the yard operator information about a variety of different operating conditions. Thus, whenever lamp 37 is steadily energized and lamp 38 is dark, during normal operation, the operator has a positive indication that track switch 1-16 is aligned in its normal position in accordance with an effective route command and will route any incoming vehicle to intermediate track 22. If only indicator lamp 38 is steadily illuminated, track switch l-l6 is aligned in its reverse position and will direct the next incoming vehicle to intermediate track 23. The indicator lamps 37 and 38 are actuated by the switch control circuit YW1-l6 as described in detail hereinafter. The same information for each of the other track switches is afforded by the switch position indicator lamps for those track switches.

An operatingcondition may occur in which track switch 116 is aligned in its normal" position when a route command is'stored in storage unit RSI-16 that requires track switch l-l6 to move to its reverse position and the track switch has failed to throw properly. For this malfunction, indicator lamp 37 is illuminated steadily but lamp 38 flashes on and off. If lamp 38 is illuminated steadily but lamp 37 is flashing, the operator knows the track switch is in its reverse position at a time when it should have been thrown to its normal position. The combination of steady and flashing outlet indicator lamps for any track switch informs the yard operator of this particular type of malfunction and enables him immediately to identify the track switch at which the malfunction has occurred.

If both of the position indicator lamps 37 and 38 for track switch l-l6 are intermittently energized, each affording a flashing signal to .the operator, it indicates that the switch points are open or that the switching machine for track switch l-l6 has suffered a power failure and cannot be thrown. The same indications are afforded by the position indicator lamps for all of the remaining track switches for the system.

For any of the track switches, a condition may occur in which both of the outlet indicator lamps are dark. This indicates that the track switch is in automatic operation and that there is no route command in the system, beyond the last preliminary storage unit 63 that requires the use of that particular track switch. The inlet end indicator lamps, such as lamp 36, simply indicate the presence of a vehicle in any given track switch. These lamps remain dark when there is no vehicle in the track section that encompasses the associated track switch.

Occasionally, when a vehicle stalls or otherwise fails to complete its route, it may be necessary to cancel the remainder of a route command from the system, downstream of the track switch l-16. This is accomplished, at any given track switch, by use of the manual-operating switch for that track switch. The manual-operating switch, at the track switch on the route to be cancelled that is closest to the hump, is first moved to its open" position, and then back to its automatic position. This cancels the route command from that track switch control unit and from all control units downstream thereof as described in detail hereinafter. 7

During normal automatic operation, all of the manualoperating switches WLl-16 through WL15-16 remain in the automatic position. The open position is used only for cancellation purposes, as described, or when no movement of the associated track switch is desired, as when a destinationtrack is full and additional cars are not to be forwarded to it. By momentarily actuating any of these switches to the right-hand throw" position, the associated track switch can be thrown from its reverse position to itsnormal position or vice versa.

The switch position pushbutton 56 is used when the yard operator desires to see the current operating position for all of the track switch in the yard. By actuating pushbutton 56, the position indicator lamps for all of the track switches are energized in accordance with the present operating positions of the track switches.

The Encoding Matrix FIG. 3 affords a schematic illustration of the encoding matrix 60, including the preliminary cancellation-encoding circuits, for the system of FIGS. 1 and 2. The track selector switches 40 are shown at the left of FIG. 3, each with an added designation to identify the destination track with which the selector switch is associated. Thus, the selector 40 for destination track 1 is shown in FIG. 3 as a single-pole double-throw switch 40-1, the track selector for track 2 is the single-pole double-throw switch 40-2, and so on through selector switch 40-16. Each selector switch has one normally open contact and one normally closed contact.

Track selector switch 40-1 has its movable contact connected to a power supply terminal N. The normally closed contact of switch 40-1 is connected to the movable contact of the next selector switch 40-2. The normally closed contact of selector 40-2 is electrically connected to the movable contact of the next selector 40-3, and this connection arrangement is carried out throughout the sequence of track selector switches. The connection sequence is such that if two selector switches are actuated simultaneously, only the lower-numbered selector will enter a route command in the system.

Immediately to the right of the track selectors 40, in FIG. 3, is a tabulation of the route command code used in the system. In this code, the first track switch in any route is identified by the JA level of the code, the second track switch by the .IB level of the code, the third track switch by the .IC level, the fourth by the JD level and the fifth by the JE level. This simple system of identifying track switches in the code is carried out throughout the system. The code changes by one level for each track switch downstream in a given route; that is, the JB level of the code becomes the initial or JA level at the second switch downstream in the yard, as will be made more apparent by the succeeding description of the specific storage and control circuits for the yard. In the code tabulation presented in FIG. 3, a zero identifies a normal position for a track switch and has the electrical significance of a zero-level signal. In the code, a l identifies a reverse" track switch position and has the electrical significance of a pulse of positive polarity at a level of approximately 3 to '5 volts. In FIG. 1, normal is directed toward the top of the drawing, reverse toward the bottom. It should be understood that the code arrangement adopted for the specific system described in connection with FIGS. 37 is arbitrary in nature and that other codes for identifying routes through the classification yard can be utilized as desired.

The normally open contact of track selector 40-1 is electrically connected, through a diode, to a conductor for generating an actuating signal. The normally open contacts of the remaining selectors 40-2 through 40-16 are each connected to conductor 80 through a separate diode. Accordingly, whenever any of the track selectors is actuated by the yard operator, closing its movable contact upon its normally open contact, a circuit is completed from the power supply terminal N through the track selector switch to the conductor 80. Conductor 80 is connected to the light source of an optical relay 90, the light source in turn being connected to a power supply terminal B+.

Since the code for track selector switch 40-1 is all zeros, and requires the positioning of all track switches leading to destination track 1 in the normal position (FIG. 1), there are no additional output connections necessary for this track selector. The next track selector 40-2, however, has an additional output connection from its normally open contact, through a diode, to a conductor that corresponds to the fifth or IE level in the code. Similarly, every track selector having a code I in the fifth level is connected through a separate diode to conductor 85. Conductor 85 is connected to the light source of an optical relay 95, that light source being returned to the 13+ supply.

Each of the track selectors 40 that has a l in its code designation at the first (.IA) level of the code has its normally open contact connected through a diode to a conductor 81. Conductor 81 is connected to the light source in an optical relay 91. Each track selector that has a code designation including a l in the second (JB) level of the code has its normally open contact connected through a diode to a conductor 82 that is intum connected to the light source of an optical relay 92. Each track selector with a code designation including a l in the third (JC) level of the code has its normally open contact connected through a diode to a conductor 83 that is connected to the light source of an optical relay 93. And all of the track selectors that have a 1" designation in the fourth (JD) level of the code are connected by individual diodes to a conductor 84 that is connected to the light source for an optical relay 94. In each instance, the light source of the optical relay is connected to the B+ supply.

In optical relay 90, the output resistor of the relay has one terminal connected to the power supply terminal N. The other terminal of this resistor is connected to the input of an inverting amplifier 100, the input connection having a capacitor connected to it and returned to system ground. The output from amplifier 100 is taken at a conductor 110 that is connected to the first preliminary storage unit 61 '(FIG. 4).

The output conductor 110 (FIG. 3) is also connected to one input of an inverting OR amplifier 121 that is connected to another inverting OR amplifier 122 to'afford a flip-flop circuit 126. Thus, the output of amplifier 121 is connected to one input of amplifier 122 and the output of amplifier 122 is connected to the second input of amplifier 121. The output of the flip-flop circuit 126 is taken from the output of amplifier 122, which is connected to the input of an inverter 123. The output 124 of inverter 123 is connected to preliminary storage unit 61 (FIG. 4). The second input to inverter 122 comprises a conductor 125 that receives a signal from storage unit 61 (FIG. 4) as described more fully hereinafter.

The light relay 91 that corresponds to the first (JA) level of the route command code has its output resistor connected to the power supply terminal N, the other terminal of the resistor being connected to the input of an inverter 101. The output of inverter 101, designated by reference numeral 111, is the first (.IA) level code signal that is supplied to storage unit 61 (FIG. 4).

The output connections for the remaining optical code relays 92 through 95 are similar to that for relay 91. Thus, the output resistors of each of relays 92, 93, 94 and 95 are electrically connected to the inputs of the inverting amplifiers 102, 103, 104 and 105, respectively. The output conductors for transmission of the code data signals to preliminary storage unit 61, for the remaining four levels of the code, are conductors 112, 113, 114, and 115, respectively.

The cancellation signal encoding circuits are shown in the upper right-hand corner of FIG. 3. As illustrated therein, each of the cancel switchesSl through 54' is a single-pole, singlethrow, normally closed switch. The movable contact of switch 54 is electrically connected to the power supply terminal N. The fixed contact of cancel switch 54 is electrically connected to the movable contact of cancel switch 53. The fixed contact of cancel switch 53 is electrically connected to the movable contact of cancel switch 52 and the fixed contact of the latter switch is electrically connected to the movable contact of cancel switch 51.

The fixed contact of cancel switch 53 is also connected to one terminal of the light source in an optical relay 96, the other terminal of the light source being connected to the power supply terminal B+. The fixed contact of cancel switch 52 is electrically connected to one terminal of the light source in an optical relay 97. The fixed contact of cancel switch 51 is electrically connected to the light source in an optical relay 98. The light sources for relays 97 and 98 are also connected to the 13+ supply.

The output resistors for optical relays 96, 97 and 98 each have one terminal connected to the power supply terminal N. The remaining terminal of the output resistor in optical relay 98 is connected to conductor 118 that connects to the first preliminary storage unit 61 (FIG. 4). The output from optical relay 97 is taken at a conductor 117 that is connected to the second preliminary storage unit 62, FIG. 4. The output conductor 116 for optical relay 96 is electrically connected to the third preliminary storage unit 63 (see FIG. 2).

In considering the operation of encoding matrix 60, FIG. 3, the actuation of track selector 40-6 by the yard operator, in recording the first route command in the system (see FIGS. 1, 2) may be taken as a starting point. When the operator actuates selector switch 40-6, the movable contact of the switch closes upon its normally open contact and completes an electrical circuit to conductor 82. This affords an operating circuit that extends from the power supply terminal N through selector 40-6 and conductor 82 to the light source for optical relay 92 and then to the B+ supply. When the light source for optical relay 92 is energized, the output resistor of the relay is greatly reduced in impedance and completes and input circuit connection from the power supply terminal N to the inverter 102. This produces a positive-going output signal on conductor 112 that is supplied to the route storage unit 61, FIG. 4. Since track selector switch 40-6 is not provided with an electrical connection to any of the other code conductors 81', 83, 84 or 85, the remaining optical code relays 91, 93, 94 and 95 remain dark and there are no positive-going output signals on any ofthe conductors 1 11, 113, 1 14 and 1 15.

The actuation of track selector switch 40-6, however, also completes an electrical circuit to the conductor 80, an energizing circuit for the light source of optical relay 90 that results in the application of a signal to the input of inverting amplifier 100. Accordingly, a positive-going output signal is supplied, on conductor 1 10, to route storage unit 61 (FIG. 4). This same signal is supplied to the input of flip-flop circuit 126. The flip-flop circuit is actuated and supplies an input signal to amplifier 123, producing a positive-going output signal on conductor 124 that is supplied to storage unit 61. Flip-flop circuit 126 is utilized to prevent the code information developed by actuation of switch 40-6 from entering the first preliminary storage unit 61 more than one time. As soon as the code information is stored in the first preliminary route storage unit 61, as described more fully hereinafter, a route stored signal is supplied to inverter 122 on conductor 125. This signal resets flip-flop circuit 126 to its original condition and prevents the code data from being entered a second time in route storage unit 61.

When the operator subsequently actuates tack selector switch 40-12 to record the second route command in the system, the operation proceeds essentially as described above except that the only code signal is developed at the first-level output conductor 111, since selector 40-12 is connected only to the first-level internal code conductor 81 of the encoding matrix. As before, actuation of the selector switch completes a circuit to conductor 80 to produce output signals at conductors and 124. For the third route command, the operator actuates track selector switch 40-16. This produces output code signals on conductors 111, 112, and 113, corresponding to the code for track 16 which has one values in each of the first three code levels. Subsequent actuation of selector 40-3 develops a code signal on conductor 83. As before, for each actuation of any track selector, output signals are produced at conductors 1 10 and 124.

For operation of the route storage cancellation portion of encoding matrix 60, as shown in FIG. 3, it may be assumed that the operator desires to cancel the route command for destination track 16 previously recorded in preliminary storage unit 62 (see FIG. 2). To cancel this route command, the operator actuates cancel switch 52, which opens the energizing circuits for the light sources in optical relays 97 and 98. This produces output signals on each of conductors 117 and 118 and these signals are utilized to clear preliminary storage units 62 and 61, respectively. The cancellation operation is described in greater detail hereinafter in connection with FIG. 4. It should be noted that actuation of cancel switch 54 cancels all previously recorded route commands from storage unit RSI-16 back to the first storage unit 61 (FIG. 2). Each of the cancellation switches 52 and 53 operate to cancel all upstream route command information. Cancel switch 51- is effective only with respect to preliminary storage unit 61. There is no downstream propagation of cancellation signals in the preliminary storage units of the system.

The Preliminary Route Storage Units FIG. 4 illustrates the first two preliminary route storage units 61 and 62 in substantial detail. As shown therein, route storage unit 61 comprises an inverter 131 having its input connected to conductor 110 from encoding matrix 60 (FIG. 3), the output of inverter 131 being connected to one input of an inverting AND gate 132 sometimes referred to as the input control gate. Gate 132 also has a second input connection, conductor 124, direct from encoding matrix 60 (FIG. 3). Input gate 132 is shown as having additional inputs but these are not used in this stage of the system.

The output of gate 132 is connected to one input of an inverter 133 that is combined with another inverter 134 in an input control flip-flop circuit 135. Thus, the output of inverter 133 is connected to one input of inverter 134 and the output of inverter 134 is connected to the second input of amplifier 133. The second input to amplifier 134 is a clock signal input to which a clock signal D is supplied. The clock signal circuits are not illustrated in the drawings; the time relationship of the several 'clock signals employed in the illustrated circuits is shown in FIG. 6. The particular circuits used to develop the clock signals are not critical to the invention. The clock B signal times operation of gate 132, being applied .thereto through a diode 145.

The output of inverter 133 in the input control flip-flop circuit 135 is also connected to one input of an AND gate 136. The other input of AND gate 136 is the clock signal B2. The output of AND gate 136 is a route storage received signal that is supplied to the conductor 125 in the feedback circuit to the dual-entry control flip-flop 126 in encoding matrix 60'(FIG. 3).

The output of AND gate 136 is also supplied to one input of an amplifier 137 that is combined with a second amplifier 138 in a route stored flip-flop circuit 139. Thus, the output of amplifier 137 is connected to one input of amplifier 138 and the output of amplifier 138 is connected to the second input of amplifier 137. The output of amplifier 138 in the route stored flip-flop 139 is also connected back through a diode 141 to an auxiliary input circuit of input gate 132. In addition, the output circuit 142 of route stored flip-fip circuit 139 is connected to the next storage unit 63 as described more fully hereinafter.

At the left-hand side of route command storage unit 61, FIG. 4, conductor 124 from encoding matrix 60 is connected to an inverting OR gate 144, sometimes referred to as the propagating cancel control gate of the storage unit. Gate 144 is not used in storage unit 61 or in the other preliminary storage units; it is illustrated because it its preferable to have all route storage units of uniform construction.

An inverting AND gate 146 is incorporated in storage unit 61 and is provided with two input circuits. One of these inputs is connected to the cancel signal conductor 118 from encoding matrix 60. The other input to gate 146 is the clock A signal. Gate 146 is sometimes referred to hereinafter as the operator cancel control gate.

The output circuits of the two cancel gates 144 and 14.6-are connected together and constitute one input circuit for an inverter 147 that is combined with an inverter 148'in a. cancel flip-flop circuit 149. The output of amplifier 147 is connected to one input of amplifier 148 and the output of amplifier 148 is connected to one input for amplifier 147. The second input to inverter 148 in cancel flip-flop circuit 149 is taken from the clock D source. There is an output connection from the output of amplifier 148 through a diode 151 to the auxiliary input to input gate 132. There is a special setting input to amplifier 147 in flip-flop circuit 149 through a diode 152. Another input to amplifier 147 is provided, on a conductor 150, as described hereinafter. An additional input is shown for amplifier 147, but is not used in this first storage unit of the system.

The output 156 of amplifier 147, which has a capacitor 153 connected thereto that is returned to system ground, is connected to a'reset AND gate 155 by a cancel output conductor 156. The second input to reset gate 155 is the clock C signal. The output of reset gate 155 is connected to a reset conductor 157 that is connected to one of the inputs of amplifier 138 in the route stored flip-flop circuit 139.

The route command storage unit 61, as illustrated in FIG. 4, includes five inverting AND gates 161, 162, 163, 164 and165, each of which is an input gate for one of the five code data signals that may be transmitted to the storage unit from encoding matrix 60. Each of the gates 161 through has two inputs. The code signal conductor 111 from encoding matrix 60 is connected to one input of gate 161. The code signal conductor 1 12 from the encoding matrix is connected to one input of gate 162. Code conductors 113, 114 and 115 are connected to the inputs of gates 163, 164 and 165, respectively. The second input to each of the gates 16] through 165 is supplied from the output of inverter 133 in the input control flip-flop circuit 135.

The output of gate 161 is connected to an inverting OR amplifier 166 that is combined with a second inverting OR ampli fier'l67 in a first (JA level) level) data storage flip-flop circuit 171. Within flip-flop circuit 171, the output of inverter 166 is connected to one input of inverter 167 and the output of inverter 167 is connected to the second input of inverter 166. The second input to inverter 167 is taken from reset conductor157.

Each of the code data input gates 162, 163, 164 and 165 is similarly connected to one of four data storage flip-flop circuits 172, 173, 174 and 175, respectively. Inasmuch as flipflop circuits 172 through 176 are similar in construction to flip-flop circuit 171, and have the same input connections except for the code data input gate, the flip-flop circuits have not been shown in detail. I

The output connection from the first .IA code level flip-flop circuit 171 in storage unit 61, taken from the output of gate 166 therein, is connected to a first code data input gate 261 in storage unit 62. Similar connections are made from data storage flip-flop circuits 172, 173, 174 and 175 in storage unit 61 to data input gates 262, 263, 264 and 265 in storage unit 62.

There is one other circuit in the first route command storage unit 61, FIG. 4, a same-route flip-flop circuit 185. It comprises two inverting OR amplifiers 186 and 187 each having its output connected to one of the inputs of the other amplifier. A second input 225 for amplifier 186 is derived from the succeeding storage unit 62 as explained more fully hereinafter. There is a third input to amplifier 186, but it is not used in storage unit 61; it is employed in track switch storage units. The second input to amplifier 187 in the same-route flip-flop circuit 265 is a reset input taken from reset conductor 157. The output of inverter 187 is connected to the feedback circuit 150 leading back to cancel flip-flop 149.

Route storage unit 62, as illustrated in FIG. 4, in its internal construction, is a duplicate of route storage unit 61. In fact, all of the storage units of the system are interchangeable modules that are duplicates of each other, insofar as their internal construction is concerned. There are variations in the external connections, depending upon the position of the route storage unit in the system. Consequently, storage unit 62, as illustrated inthe drawing, has been substantiallysimplified, with the internal construction of the flip-flop circuits omitted. In storage unit I 62, individual circuits have reference numerals corresponding to those in storage unit 61 but increased by 100.

The input inverter 231 in storage unit 62 has its input connected to the conductor 142 that is the output circuit for route stored flip-flop circuit 139 in the preceding stage. The output of inverter 231 is connected to one of the inputs of the input AND gate 232, the only effective input, other than the clock B input, for gate 232.

In storage unit 62, propagating cancel control gate 244 is again not utilized. As in the first storage unit, one of the inputs to the operator cancel control gate 246 is from the clock A source. The other input to gate 246 is the cancel signal conductor 1 17 that originates in encoding matrix 60 (FIG. 3).

As in storage unit 61, storage unit 62 provides a clock D input to input control flip-flop circuit 235 and to cancel flipflop circuit 249. Cancel flip-flop circuit 249 has an input on circuit 250 from the same-route flip-flop 285 of storage unit 62.

The connections for the route stored flip-flop 249 in storage unit 262 are the same as in thepreceding storage unit. The output conductor 242 from route stored flip-flop 1239 connects to the next storage unit 63. The same-route flip-flop circuit 285 of storage unit 62 is provided with an input from the route stored gate in the succeeding storage unit 63.

In storage unit 62 the AND gate 236 that affords the actuating input to route stored flip-flop 239 is also connected back, by conductor 225, to the input of the same-route flip-flop circuit 185 in the preceding storage unit 61. The connections of the reset gate 255 in storage unit 62 remain unchanged. The input connections for the data input gates 261 through 265 are taken from the data storage flip-flop circuits 171 through 175, respectively, as described above. Gates 261 through 265 actuate five data storage flip-flop circuits 271 through 275, respectively. Each of the data storage flip-flop circuits 271 through 275 is provided with an output connection to the next storage unit 263.

The recording of a route command in storage unit 61 starts at inverter gate 131, which receives an actuating signal from encoding matrix 60, on conductor 1 10, each time a new route is to be entered in the system, as described above. The output of gate 131 is a positive-going signal that actuates AND gate 132 conjointly with the clock B signal and the signal supplied on conductor 124 from encoding matrix 60.

AND gate 132 is not actuated if a route command is already stored in storage unit 161; under those circumstances, the AND gate is inhibited by the connection from the route stored flip-flop 139 through diode 141 as explained more fully hereinafter. Furthermore, AND gate 132 is not enabled if a cancel operation is proceeding in storage unit 61, being inhibited by the feedback connection from cancel flip-flop circuit 149 provided by diode 151.

If the inhibiting conditions noted above are not present, input AND gate 132 is actuated by the signals from encoding matrix 60 and supplies a signal to amplifier 133 that flips input control flip-flop circuit 135. When circuit 135 is flipped, it produces a positive output signal, affording an enabling signal to each of the data input gates 161 through 165. Any of the AND gates 161 through 165 that also receives a code signal from encoder 60, as described above, is actuated, and supplies an input signal to its associated data storage flip-flop circuit. Thus, the data storage flip-flop circuits 171 through 175 are selectively actuated in accordance with the route command that has been entered in encoding matrix 60 by the yard operator.

The positive output signal from input control flip-flop 135 also enables AND gate 136. AND gate 136 is actuated by the clock signal B2 and produces an output signal that flips the route stored flip-flop circuit 139. The output signal from gate 136 is also fed back to the information coding matrix on conductor 125 to prevent dual entry of the route command.

' When route stored flip-flop circuit 139 is actuated, it effectively cuts off input gate 132, through the feedback circuit comprising diode 141. This same signal is supplied, by conductor 142, to the input inverter 231 in storage unit 62. If the proper operating conditions are present in storage unit 62 (no route stored, no cancellation operation proceeding), the route command data that has been recorded in storage unit 61 is promptly recorded in storage unit 62. In this manner, each individual route command is propagated through the series of preliminary storage units, being entered in each succeeding storage unit as soon as that storage unit is cleared and ready for the next route command. In each storage unit,the input control flip-flop circuit, such as circuit 135 in storage unit 61, is reset by the clock D signal as a part of preparation for the next recording operation.

Clearing information from each of the data storage units is, of course, as important as recording of route commands in those units. Storage unit 61 is automatically cleared whenever a route command has been transferred downstream to storage unit 62. This is accomplished by the feedback connection 225 from gate 236 in storage unit 62 to the same-route flip-flop 185 in storage unit 61. When the route command is entered into storage unit 62, gate 236 is actuated in the course of the recording operation. The resulting output signal on conductor 225, in addition to actuating the route stored flip-flop 239, flips same-route circuit 185.

When the same-route flip-flop 185 is actuated, a positive output signal is developed on conductor 150 and this signal is supplied to the input gate 147 of cancel flip-flop 149.- This actuates the cancel flip-flop and supplies an enabling signal to reset gate 155. Thereafter, at a time determined by clock signal C, the reset gate supplies a reset signal to reset conductor 157. This resets all of the data storage flip-flops 171 through 175. In addition, the reset signal resets the route stored flip-flop 139. Subsequently, the clock signal D resets cancel flip-flop 149, restoring storage unit 61 to its original operating condition, ready to receive another route command.

If any of the cancel switches 51 through 54 (FIG. 3) is actuated by the yard operator, an input signal is supplied on line 118 to the operator cancel control gate 146 in storage unit 61 (FIG. 4). At a time determined by clock signal A, cancel gate 146 produces an output signal that is supplied to gate 147 and actuates the cancel flip-flop circuit 149. The clearing operation then proceeds as described above, in the same manner as if cancellation had been initiated automatically by transfer of a route command to storage unit 62. That is, any route command stored in unit 61 is cleared, the route stored flip-flop 139 is reset, and the input control and cancellation flip-flops and 149 are reset bythe clock D signal to establish the conditions necessary for a subsequent route command recording operation.

The cancellation and clearing operations in storage unit 62 proceed in the same manner as for storage unit 61 and hence need not be described in detail. The only difference is that storage unit 62 cannot be cleared by actuation of the operator's cancel pushbutton 51, since that cancel switch oes not produce an output signal on conductor 117 (FIGS. 3 and 4) and cannot actuate the cancel gate 246 of storage unit 62. However, cancellation by the operator is effected upon actuation of any of the cancellation switches 52, 53 or 54.

It may be noted that the same'route flip-flop is not essential to the preliminary storage units, although it is useful in the track switch storage units described hereinafter particularly in connection with FIG. 5. The signal from gate 236 that actuates the same-route flip-flop 185 could be fed back directly to cancel flip-flop circuit 149. As mentioned previously, the complete circuits for a practical system have been illustrated in the drawings, including surplusage in some instances, to afford storage units that are completely interchangeable throughout the system.

The Track Switch Storage Units FIG. 5 illustrates the first three track switch storage units RSI-l6, RS1-11, and RS12-16, storage units RSI-16 and RS1-11 being shown in substantial detail. The internal construction of these storage units is the same as. described above for preliminary storage units 61 and 62, but the external connectionsare somewhat different and'the operations, particularly in clearing stored route command data, are more complex. Because vthe internal construction remains unchanged, only a brief description is afforded. The circuits in storage unit RSI-16 are identified by reference numerals corresponding to those in storage unit 61 but increased by 200, whereas the same reference numerals are again. used in storage unit RSI-1 1, but increased further by a factor of 100.

In storage unit RSI-16, the inverter 331has an input connection from the route stored flip-flop circuit in the preceding storage unit 63, the connection corresponding to that between storage units 61 and 62 as illustrated in FIG. 4. The output of inverter 331 is the sole enabling input required for input gate 332; in this regard, the input arrangement forstorage unit RSI-16 is the same as for the other preliminary storage units. As in the preliminary storage units, the propagation cancellation gate 344 is not utilized in storage unit RS1-l6.

The inputs to the cancellation flip-flop 349 in storage unit RS1-16'include a connection from the track switch control circuit YW1-16 (FIG. 2) on the conductor 390. This connection affords additional means for actuating cancel flip-flop 349 to clear storage unit RS 1-16 as described hereinafter. An additional automatic cancel input 391 to flip-flop 349 is not used in unit RSI-16.

The input to the operators cancelgate 346 in storage unit RSI-16 is derived from the manual-operating switch WL1-16, or from cancel pushbutton 54 (FIGS. 1 and 2).

As noted above, the internal connections and components for storage unit RS1-16 are the same as for the preliminary storage units. The track switch storage unit includes an input control flip-flop 335, a route stored flip-flop 339, and a sameroute flip-flop 385, with an actuating gate 336 for the route stored flip-flop 339. As before, the output ofv gate 336 is connected back to the preceding storage unit 363 by a conductor 325. The data storage circuits remain unchanged andinclude the input gates 361 through 365 all controlled by the input flip-flop 335 and by individual data signals from the preceding storage unit 63. These data input gates actuate thev data storage flip-flops 371 through 375, each of which has a reset connection from reset gate 355.

Storage .unit RSl-ll is again similar in construction and includes an input inverter 431 actuated by signals from the route stored flip-flop 339 of storage unit RSI-16, suppliedon conductor 342. Inverter 431 is connected to an input control gate 432. But the input connections to gate 432 are more complex in storage unit RS 1-11 than in preceding units. Thus, an input to gate 432 ,is provided .from the switch control circuit YW1-l6 for the preceding switch, on conductor 392. Another input to gate 432 is taken, on conductor- 424, from the NOT output of data storage flip-flop 371, the data storage flip-flop for the first code level, in the preceding storage unit RSI-16.

The propagating cancel control gate 444 that is incorporated in storage unit RSI-1 1 is provided with three inputs in addition to its clock B input. One of these inputs is taken from V the cancel flip-flop 349 in the preceding stage, on conductor 356; as seen from FIG. 5, the input 356 to gate 444 in storage unit RSI-11 is the same as in the input to reset gate 355 in storage unit RSI-16. The third active input to the propagating cancel control gate 444 is circuit 389 fromthe same-route flip-flop 385 in the preceding stage, by means of conductor 389.

The cancel flip-flop circuit 449v that is incorporated in storage unit RSI-l1, in addition to its actuating input from cancellation gates 444 and 446, has two inputs from the switch control circuit YWl-ll on conductors 490 and 49.1. The connection 490 is the same as afforded by conductor 39.0 in the preceding track switch storage unit. The inputs to the operators cancel control gate .446 are derived from the manual operating switch WLl-ll (FIGS. 1 and 2) and from the clock Asource. l

Storage unit RSI-11 includes an input control flip-flop 435 that is connected in the same manner as in previously described storage units. As before, flip-flop 435'is connected to a gate 436 and to a series of data input gates 461 through 464. There are only four data input gates in storage unit RSI-11 since there are a maximum of three track switches downstream from the track switch 1-11 to which the storage unit pertains. To preserve a completely modular construction, the fifth level of data storage could be included in storage unit RS 1-1 1 but it would not be used.

The inputs to data storage gates 461,462, 463 and 464 are taken from data storage flip-flops 372, 373, 374 and 375, respectively. That is, the information from the data storage flip-flop 371' in storage unit RSI-16 is not transferred downstream to storage unit RSI-l l. The reason for this is that the data that may be stored in flip-flop circuit 371 pertains only to track switch 1-16 and is not pertinent to the positioning of succeeding track switches. Gates 461 through 464 actuate four corresponding data storage flip-flops 471 through 474, respectively.

Storage unit RSl-ll includes a route stored flip-flop 439, a same-route flip-flop 485, and a reset gate 455, all having internal connections as described 'in relation to preceding storage units. The same-route flip-flop 485 has two inputs from the succeeding storage units RSI-5 and RS6-11. Output connectionsare taken from the same-route flip-flop circuit 485 to both of the downstream storage units. Data storage flip-flop 471 is not connected to the downstream storage units because the information that it records pertains only to track switch 1-11 and is not pertinent to positioning of track switches l-S and 6-11. An output connection is made from data storage flip-flop 472 to both of the downstream storage units RSI-5 and RS6-11. Output connections are also made from data storage flip-flops 473 and 474 to both of the downstream storage units RSI-5 and RS6-11, since there are two additional track switches beyond each of track switches l-5 and 6-11. Output connections are also afforded from cancel flipfiop 449 and route stored flip-flop 439 to both of the downstream storage units RSI-5 and RS6-11.

An output connection, on conductor 424, is taken from data storage flip-flop 371 in storage unit RSI-16 to track switch control circuit YWl-l6. The corresponding connection from storage unit RSI-11 to track switch control circuit YWl-l l is indicated by conductor 524.

Storage unit RS12-16 is shown in FIG. 5 as a single element. The internal construction is identical with that of storage unit RSI-11 and the external connections are the same except that connections from storage'unit RSI-11 indicated as going to track switch control circuit YWl-ll are taken from storage unit RS12-l6 to track switch control circuit YW12-16 (FIG. 2). From storage unit RSl2-16, the downstream route storage connections are made to storage units RS12-14 and RS15-16. The upstream connections of storage unit RS 1-1 1 to unit RS12-16 vary only in that conductor 424 is not connected to storage unit RS12-16, the corresponding information for the latter being derived from the other output 396 of flip-flop circuit 371.

Recording of a route command in storage unit RSI-16, which is the last of the preliminary storage units and also the first of the track switch storage units, proceeds essentially as described above with respect to storage units 61 and 62. Thus, the initiation signal for recording a route command in storage unit RSI-16 is the route stored signal from the preceding storage unit 63 that is supplied to inverter 331 to actuate input gate 332. Gate 332 is opened only if no route command has already been stored in storage unit RSI-l6, as determined by the feedback circuit from route stored flip-flop circuit 339 through diode 341 to gate 332. Recording of the new route command is also precluded if a cancellation operation is taking place in storage unit RSI-16, this control function being accomplished by the feedback circuit from cancel flip-flop 349 through diode 351 to input gate 332. If both of these prerequisite conditions are satisfied, with no route command clock signal B2 to actuate the route stored. flip-flop circuit. 339. Moreover, the signal from input control flip-flop 335' enables data storage input gates 361 through 365, which actuate data storage fIip-flop circuits 371 through 375 selectively in accordance with the code data stored in the preceding stage. In this manner the route command from storage unit 63 is recorded in storage unit RSI-16.

The same recording operation takes place in storage unit RSI-11, but subject to some additional controls. The recording operation in storage unit RSI-11 is initiated by the signal supplied to inverter 431, on conductor342, from the route stored flip-flop circuit 339 in the preceding stage. Again, the output signal of inverter 431 is applied to input gate 432.

Storage unit RSI-11 should receive route commands from storage unit RSI-16 if, and only if, those route commands pertain to routes-in which track switch 1-16 is in its normal" position. Routecommands pertaining to reverse positions of track switch l-16 are not applicable to track switch 1-11 or to its storage unit. It is for this reason that the connection afforded by conductor 424 is utilized to condition gate 432 for operation only when the command data stored in storage unit RS 1-16 will route an incoming vehicle to track switch 1-11.

Before a route command is recorded in storage unit RSI-11, it is desirable that the track switch 1-16 be aligned to route a vehicle to track switch 1-11. It is for this reason that the connection on conductor 392 is made from track control circuit YW1-16 (FIG. 2) to input gate 432 of storage unit RSI-l1 (FIG. 5). Of course, in storage unit RSI-11, the other conditions referred to above as prerequisite toa recording operation are observed; the feedback connection from flipflop circuit 439 prevents recording of a new route command when a command is already recorded in the storage unit, and the feedback connection from cancel flip-flop 439 to gate 432 prevents a recording operation when a cancellation operation is taking plate.

Clearing of data from route storage unit RSI-l6 is essentially similar to the clearing operations described above in connection with storage unit 61 and 62. The basic clearing operation requires actuation of cancel flip-flop circuit 349, producing an enabling signal that is supplied to reset gate 355. At a time'determined by the clock signal C, reset gate 355 produces anoutput signal that resets the route stored flip-flop 339 and the same-route flip-flop 385. This same reset signal is supplied to and clears all of the data storage flip-flop circuits 371 through 375. Cancellation of data in storage unit RSI-16, when initiated by the yard operator, proceeds in much the same manner as for the preliminary storage units. The operator actuates the manual operating switch WL1-l6 associated with track switch 1-16 to its open" position, producing a signal of short duration that is supplied to the operator's cancel gate 346. Gate 346 is enabled at a time determined byv the clock signal A,

I which repeats at an interval short enough to assure actuation of the gate. The gate produces an output signal that is supplied to cancel flip-flop 349 and initiates the clearing operation described above. This is a propagating cancel operation that can extend downstream of storage unit RSI-l6, as described more fully hereinafter in connection with storage unit 1-1 1.

In storage unit RS 1-16, as in the preceding storage units 61 through 63, the other cancel input gate 344 is not utilized. The corresponding gates are employed for cancellation operations only in the storage units downstream of track switch 1-16, the basic operation being described in relation to storage unit RS l-l 1.

For storage unit RSI-11, however, there are two additional sources of signals that can initiate a cancellation or clearing operation, both being derivedfrom the track switch control circuit YWl-ll. The first is a track cancel signal, applied to cancel flipflop circuit 449 on conductor 490, that indicates a vehicle has cleared track switch 1-11. The second is an automatic cancel indicating the occurrence of a catchup in the yard, in the track section encompassing track switch 1-11. This automatic cancel signal is supplied to cancel flip-flop 449, from track switch control circuit YWl-ll, on line 491. Both the track cancel and the automatic cancel signals are supplied directly to the cancel flip-flop circuit and specifically to the inverter in theflip-flop circuit corresponding to inverter 147 illustrated in FIG. 4. v

In route command storage unit RS 1-16, the internal operations necessary to efiect a clearing of a recorded route command are the same as in the previously described storage unit except that no automatic cancel is needed. They are initiated by actuation of cancel flip-flop 349, which energizes reset gate 355 to supply a clearing or reset signal to all of the flip-flop circuits 339, 385, and 371 through 374.

A cancellation operation initiated by the yard operator again is effected in storage unit RSI-1 l by an input signal supplied to cancel gate 446. The signal originates by the operator actuating the manual control switch WLl-ll (FIGS. 1 and 2) to its open condition. The output signal from cancel gate 446 is supplied to cancel flip-flop 449 to afford a clearing operation as described above.

In storage unit RS11 1, provision is again made for direct actuation of cancel flip-flop 449 by signals received from the track switch control circuit YWl-ll that is incorporated in the same control unit with storage unit RS1-11 (see'FlG. 2). The track cancel signal that indicates a vehicle has entered track switch l-ll is supplied to cancel flip-flop circuit 449 through conductor 490. The automatic cancel signal indicating occurrence of a catchup is applied to the cancel flip-flop circuit by means of the conductor 491. The origination of the track cancel and automatic cancel signals is described in connection with FIG. 7.

ln storage unit RS 1-11, there is anothermeans for initiating a cancel signal, comprising the downstream propagating cancel gate 444. Gate 444 is enabled, at a time determined by the timing signal B, if three different conditions are present in the system. The preceding storage unit RSI-16 must have recorded in it a route command that requires the use of track switch 1-11; this condition is signalled to gate 444 by the connection from data storage flip-flop circuit 371 in the preceding stage afforded by conductor 424. The same route command must be stored in both of the storage units RSI-l6 and RSI-11. This condition is signalled to gate 444 by the connection from the same route flip-flop 385 in the preceding stage to gate 444 that is afforded by conductor 389.

The third condition necessary to actuate the propagating cancel gate 444 is a cancel signal from the preceding storage unit RSI-l6 occurring a time which indicates that downstream storage of the same route command should be cancelled. The signal conveying this information to gate 444 is derived from cancel flip-flop circuit 349 in the preceding storage unit through the connection indicated by conductor 356. It should be noted that the downstream storage unit RSI-l 1 can utilize the output signal from the preceding stage cancel flip-flop circuit 349 only at time B, since gate 444 requires an input from the clock B source in order to open. Accordingly, other cancellation operations occurring in storage unit RSI-16, particularly the track cancel operation, are not propagated through gate 444. The output of gate 444 affords the same cancellation operation as described above, being connected to cancellation flip-flop circuit 449 in the same circuit with the output of the operators cancel gate 446.

There is an additional means for clearing all of the preliminary storage units and all of the track switch storage units that has not been discussed above in connection with either of FIGS. 4 or 5. An auxiliary reset input for each of the cancellation flip-flop circuits is incorporated in the storage unit circuitry as indicated by the connections to cancel flip-flop circuits 149, 249, 349 and 449 afi'orded by diodes 152, 252, 352 and 452 respectively (FIGS. 4 and 5). An input signal supplied to these diodes and to the corresponding circuits in the other route command storage units actuates all of the cancel flipflop circuits to initiate a clearing operation for the complete storage capacity of the system. This clearing means it utilized primarily to reset the system when it has been shut down, to assure a starting condition in which'all storage units are conditioned to receive new route commands.

As noted above, the same-route flip-flop circuit (e.g., circuit 485 in storage unit RSI-11) controls the propagation of cancel signals in a downstream direction in the track switch storage units. The input signals to the same-route flip-flop circuit, in each storage unit, actuate the same-route flip-flopcircuit to indicate that the same code'has been stored in the downstream storage unit that is already present in the upstream unit. When the routes stored are no longer the same, which condition is reached when a new route command is recorded in the upstream storage unit, the same-route flip-flop circuit is reset by the output signal from the reset gate (e.g., gate 455 in storage unit RSI-l 1). The same-route flip-flop circuit also is effective to prevent the occurrence of cancellation operations out of sequence.

As indicated above, intermediate storage may be necessary between two track switches, particularly where a long intermediate track is involved; see intermediate storage unit 75 in FIG. 2. The intermediate storage unit may utilize the same construction as described above for the preliminary and track storage units, with the input and output circuits connected so that the route command will advance'when the downstream track switch storage unit is empty and will be cancelled when the stored route command has been accepted by the downstream storage unit and has been cancelled in, the upstream storage unit. The principal difference for an intermediate storage unit, as compared with a track switch storage unit such as storage unit RSI-l1, is the omission of the clearing inputs from a track switch control circuit.

The Switch Control Circuits FIG. 7 is a schematic diagram of switch control circuit YWl-ll, which is typical of the switch control circuits utilized throughout the system. The switch control circuit performs three basic control functions. One of these control functions is the actuation of track switch 11 1, the second function is control of the switch position indicators on the operator's console, and the third function is route advancement.

The circuits for actuation of track switch 1-11 are illustrated in the upper portion of FIG. 7. They comprise an inverter circuit 501 having an input taken on conductor 442 from the route stored flip-flop circuit 439 of storage unit RSI-11 (FIG. 5). The output of inverter 501 is connected to one input of an inverting AND gate 502. Gate 502 has a second input connected by the line 524to the output of the first (JA) level code storage flip-flop circuit 471 in storage unit RSI-11 (FIG. 5).

The input connection 524 from the first level code data storage flip-flop circuit is also connected to an inverting OR gate 504 in FIG. 7. The second input to gate 504 is derived An AND gate 506 is paired with gate 505. It receives one input from OR circuit 504 and a second input from circuit 522. Gate 506 has a third input 523, taken from track circuits TKl-ll, that supplies a positive input signal to gate 506 when track switch 1-11 is not in its reverse position.

The outputs of gates 505 and 506 are coupled to the two separate inputs of inverting OR gate 507. The output of gate 507 is connected to a time delay safety circuit 508 comprising a capacitor 509 connected in series from gate 507 to the base of a transistor 511. A resistor 512 is connected from the base of transistor 511 to system ground. The collector of the transistor is grounded and the emitter is connected to the input of an inverting amplifier 513. The output of amplifier from the manual operating switch WLl-ll that is associated with track switch 1-11 at the operators console. Gate 504 is paired with a similar inverting OR gate 503that has one input connected to switch WLl-ll and a second input taken from the output of gate 502.

The output of gate 503 is connected to one input of an AND gate 505. AND gate 505 has two additional inputs 521 and 522. input 521 is derived from the track circuits TKl-ll and supplies a positive input signal when the track switch l-ll is not in its normal position. The input on circuit 522 is also derived from the track circuit for track switch 1-11 and affords a positive input signal to gate 505 when the track switch is not occupied by a vehicle.

513 is connected to the input of an inverter 514 that is in turn connected to a track switch actuator 515. Typically, actuator 515 may comprise a relay driver circuit and a relay for actuating the operating mechanism of track switch 1-11 to throw the switch, in either direction, from its present position to its alternate position.

The input signal supplied to track control circuit YW l-ll (FIG. 7) from its associated storage unit RS 1-1 1 on line 524 is positive for route commands requiring the positioning of track switch 1-11 in its normal position and is negative for routes requiring that the track switch be thrown to its reverse position. The input on line 442 from the storage unit is utilized to prevent a positive signal on line 524 from throwing the track switch when no route command has been stored in storage unit RSI-l 1 Gate 503 is actuated to produce a positive output signal whenever the route command stored in storage unit RSI-11 requires that track switch l-ll be positioned in its normal" position. Gate 504, on the other hand, when actuated by the signal from the storage unit, produces a positive output indicative of a route command requiring a reverse position for track switch 1-11. Whenever a route command is stored in storage unit RSI-11, one of the two gates 503 and 504 continuously provides a positive output signal. The manual throw signal from switch WLl-ll, on the other hand, actuates both of the gates 503 and 504 and produces a positive output signal from both gates so that it can throw the track switch in either direction.

Gates 505 and 506 determine whether the track switch 1-11 can or should be moved from its present position. Thus, if the track switch should be actuated to its normal position, indicated by a positive input to gate 505 from gate 503, and if the track switch is not presently in its normal position as indicated by a positive signal on line 521, and further if the track switch is unoccupied as indicated by a positive signal on line 522, then gate 505 is enabled and produces a positive output signal that is supplied to gate 507. Gate 506 operates in the same manner as gate 505 for actuation of the track switch to its reverse position. It receives positive signals from gate 504 and inputs 523 and 522 whenever the route command calls for reverse positioning of the track switch, the track switch is not already in the reverse position, and the track switch is unoccupied. Thus, the signals from either of gates 505 and 506 actuate OR gate 507, which produces a positive output signal until the track switch reaches its correct position or until throwing of the switch is found to be no longer desired or to be unsafe.

The time delay circuit cut 01? circuit 508 interposed between gates 507 and 513 affords a means for cutting off the actuating signal supplied to gate 513 after a limited period of time. Typically, this time is of the order of two seconds; it is related to the operating time required for the track switch to move from one of its two positions to the alternate position. The time delay cut off is employed to prevent the track switch from throwing more than one time, which could happen if the switch were obstructed and returned to its original position. The output signal from gate 513 is supplied through gate 514 to track switch actuator 514 to throw the switch.

The switch indication logic in switch control circuit YWl-ll comprise a pair of inverting amplifiers 529 and 530 having inputs taken from track circuits TKl-l 1 on conductors 521 and 523 respectively. The output of inverter 529 is connected to one input of an inverting AND gate 531 and to a conductor 592 extending to storage unit RSI- and switch control circuit YW 1-5 in control unit CUl-S (See FIG. 2).

The output of inverter 530 is connected to one input of and AND gate 532 and to the downstream control unit CU6-l l by a conductor 692. The outputs of AND gates 531 and 532 are connected to the inputs of two inverting OR gates 533 and 534, respectively. Gate 533 is connected in a driving circuit for an indicator lamp 537. The output of gate 534 is connected in a driving circuit for an indicator lamp 538. The indicator lamps 537 and 538 are located on console at the normal and reverse outlet ends, respectively, for track switch ll1(FlG. 1).

The switch indication circuitry (FIG. 7) further comprises an inverting AND gate 541 having three inputs. One of the inputs for gate 541 is connected to the track circuit 521, another is connected to the track circuit 523, and the third is taken from the output of amplifier 513 in the track switch actuation circuit. The output of gate s41-isconnected to an inverting ORgate 544 and the output of gate 544 is connected to one input of each of AND gates 531 and 532.

Another inverting AND gate 542 is incorporated in the switch indication circuitry of switch control circuit YWl-ll. Gate 542 has two inputs, one connected to the output of amplifier 513 in the track actuation circuit. The other input to gate 542 is taken from the output of OR gate 507 in the track actuation circuit. The output of gate 542 is connected to the output of gate 541 in the input circuit of gate 544. The outputs of gates 541 and 542 are also connected to an external alarm through a diode 545 and to the input of an inverter 546 that is in turn connected to a flasher AND gate 547. Flasher gate 547 has a second input derived from an intermittent power supply, shown in FIG. 7 as the flasher supply 548. The output of the flasher gate is connected to one input of each of gates 533 and 534.

There are three additional inputs to the gate 544 that controls gates 531 and 532 in the indicator lamp circuitry. One of these additional inputs comprises an inverter 549 having an input connected to the manual-operating switch WLl-ll at the operator's console. The output of gate 549 is connected through a diode 551 to gate 544. Another input to gate'544 is aflorded by a diode 552 that connects circuit 522 to OR gate 544. The third auxiliary input to gate 544 is taken from the position switch 56 through a diode 553.

- Gate 544 is the principal control element for energizing the track switch position indicator lamps 537 and 538 and performs this operation under a variety of different circumstances. The signal on line 521 from track circuits TSl-ll, which may be derived from a limit switch or cam switch associated with the switch points on the normal side of the switch, is a negative-going signal when the track switch is in its normal" position. Thus, a positive-going enabling signal is supplied by inverter 529 to gate 531 whenever track switch 1-11 is in its normal position. Similarly, there is a negativegoing signal on the track circuit line 523 that produces a positive-going signal from gate 530 that serves as an enabling signal to gate 532 whenever track switch l-ll is in its reverse" position.

The logic for gate 544 is such that for a variety of circuit conditions, the output of the gate is positive and enables gates 531 and 532 so that one or both of the lamps 537 and 538 is energized to show the present condition of track switch l-ll. Thus, whenever the yard operator actuates position switch 56 (FIG. 1), an input signal is supplied to gate 544 through diode 553 to initiate a positive output from gate 544. This causes energization of one of the indicator lamps 537 and 538, through the input circuits comprising gates 531 and 532, and indicates to the operator the present position of track switch 1-11. This indication is desirable because it enables the yard operator to check the current positions of all track switches at any given time.

A positive output from gate 544 is also produced whenever the switch points for track switch l-ll are open and the track switch is not being thrown. This control function is effected by gate 541. Thus, whenever the track switch is in an intermediate position between its normal position and its reverse position, there are positive signals on both of the conductors 521 and 523 from track circuits TKl-1l. If this condition occurs because the switch is presently being thrown, there is a negative input signal to gate 541 from the output of gate 513 in the track switch actuation circuit, and the output of gate 541 is positive. But if the track switch is not being thrown by the actuating circuit, there is a positive input to gate 541 from gate 513, producing a negative output from gate 541. This causes gate 544 to produce a positive output, but the lamps 537 and 538 are not energized because gates 531 and 532 do not receive positive enabling signals from either of gates 529 and 530, respectively. But the negative output from gate 541 does actuate an alarm, through diode 545. The location of the malfunction is shown to the operator by operation of the circuit from gate 541 to inverter'546; the negative output of gate 541 is inverted in circuit 546, supplying an enabling signal to flasher gate 547. When gate 547 is thus opened,.the flasher supply 548 actuates both of the ORv gates 533 and 534. Lamps 537 and 538 both flash on and off so that the yard operator knows it is track switch 1-11 that has hung up between its normal and reverse positions.

Another circumstance that produces a positive output signal from gate 544 is a failure of track switch 1-1l to move to a desired position within the time period established by delay circuit 508. This operation is controlled by gate 542. The input to gate 542 taken from the output of gate 507 in the track switch actuation circuit is positive whenever the track switch should be thrown. The input to gate 542 from gate 513 is negative whenever a throw signal is being supplied to track switch actuation circuit 515. But the output of gate 513 goes positive when time delay circuit 508 operates to cut off the input to gate 513. Thus, there are two enabling inputs to AND gate 542 whenever the track switch has failed to complete a throwing operation within the time period established by circuit 508.

The resulting negative output signal from gate 542 not only produces a positive output signal from gate 544', it also actuates the alarm, through diode 545, and supplies a positive signal to flasher gate'547 through inverter 546. Again, the flasher supply 548 is effectively connected to the inputs of each of gates 533 and 534, intermittently energizing lamps 537 and 538. Usually, the track switch is hung up in either its reverse or its normal position and has failed to throw to the other. Thus, one of gates 531 and 532 produces a steady output, steadily energizing the lamp indicative of the present track switch position; the other indicator lamp flashes on and off. In this manner the malfunction of track switch l-ll is signalled to the operator.

Another condition that produces a positive output from gate 544 occurs when a route command has been stored in storage unit RSI-l1 and track switch RS l-1l has been properly aligned in the position required by that route command. This operating condition is identified by gate 543. Gate 543 receives a positive signal from gate 501 indicative of the storing of a route command in storage unit RSI-11. Gate 543 also receives a positive input signal from gate 513 in the track switch actuation circuit as soon as the track switch has completed its throw. The two positive input signals to gate 543 produce a negative output signal that is supplied to gate 544, which in turn supplies a positive enabling signal to each of gates 531 and 532. One of the gates 531 and 532 is actuated, depending upon the position of track switch l-ll as indicated by the outputs of gates 529 and 530. Consequently, one of the lamps 537 and 538 is energized, indicating to the operator that a route command has been stored in control unit CUl-l l and that the associated track switch 1-11 has been aligned in accordance with the route command. 

1. An electrical control system for route switching in a railroad classification yard or the like including a plurality of track switches interconnected in a given pattern for directing vehicles along a series of routes diverging from a first track switch downstream to a given number of different destination tracks, said control system comprising: a corresponding plurality of track switch control units, one for controlling each track switch, each including a storage unit having a storage capacity sufficient to store a route command, encoded in accordance with a given destination code, to identify a route through its associated track switch and all other track switches traversed to reach any destination downstream of the associated track switch; data transmission means interconnecting said storage units with each other in a pattern corresponding to said given pattern; encoding means for entering complete route commands, one at a time, in the first of said storage units; track occupancy detection means, in each control unit, for developing position signals representative of the positions of vehicles moving through the associated track switch; clearing means in each storage unit, responsive to said position signals, for clearing the storage unit of a route command stored therein each time a vehicle traverses the track switch with which the storage unit is associated; and catchup control means in each control unit, including a timing circuit and means for actuating said timing circuit in response to position signals from two consecutive track switches including the track switch associated with that control unit, for actuating the clearing means of the control unit to clear a route command pertaining to the second of two vehicles involved in a catchup.
 2. A route-switching control system according to claim 1 in which said clearing means for each storage unit is actuated whenever a vehicle enters its associated track switch, in which said data transmission means operates to enter any route command pertaining to a given storage unit, that has previously been stored in an adjacent upstream storage unit, into the given storage unit when said given storage unit is cleared, and in which the catchup control means in each control unit is coupled to the track occupancy detection means for that control unit and for the immediate upstream control unit.
 3. A route-switching control system according to claim 1, in which said catchup control means further includes means for signalling to the yard operator the occurrence of a catchup and the track switch at which the catchup has occurred.
 4. An electrical control system for route switching in a railroad classification yard or the like including a plurality of traCk switches interconnected by tracks in a given pattern for directing vehicles along a series of routes diverging from a first track switch downstream to a given number of different destination tracks, said control system comprising: a corresponding plurality of track switch control units, one for controlling each track switch, each including a storage unit having a storage capacity sufficient to store a route command, encoded in accordance with a given destination code, to identify a route through its associated track switch and all other track switches traversed to reach any destination downstream of the associated track switch; data transmission means interconnecting said storage units with each other in a pattern corresponding to said given pattern; encoding means for entering complete route commands, one at a time, in the first of said storage units; track occupancy detection means, in each control unit, for developing position signals representative of the positions of vehicles moving through the associated track switch; and catchup control means in each control unit, including a timing circuit and means for actuating said timing circuit in response to position signals from two consecutive tracks switches including the track switch associated with that control unit, for signalling to the yard operator the occurrence of a catchup and the track switch at which the catchup has occurred.
 5. A route-switching control system according to claim 4, in which each track switch control unit further comprises a track switch actuator for throwing the associated track switch, track switch position-sensing means for determining the present position of the associated track switch, and track switch throw control means for initiating operation of said track switch actuator to throw the associated track switch in response to entry of a route command in the storage unit of the track switch control unit that requires positioning of the track switch in a position other than its present position.
 6. A route-switching control system according to claim 5 in which each track switch throw control means includes a time delay cutoff circuit for interrupting operation of said track switch actuator whenever said track switch position sensing means fails to sense completion of a throw within a given time interval.
 7. A route-switching control system according to claim 6 in which each track switch control unit further includes indicator means for signalling the yard operator upon failure of the associated track switch to complete a throw pursuant to a route command, said indicator means positively identifying the track switch associated with said control unit as the track switch that has not thrown.
 8. A route-switching control system according to claim 7 in which said indicator means includes means for signalling the present position of the track switch.
 9. A route-switching control system according to claim 5, in which each track switch control unit further includes indicator means, coupled to said track switch position-sensing means, for signalling to the yard operator the occurrence of a hangup of the associated track switch at an incompletely thrown position.
 10. A route-switching control system according to claim 5 in which the catchup control means in each control unit is coupled to the track occupancy detection means for that control unit and for the immediate upstream control unit, in which the route command for the second vehicle in a catchup is the command that is cleared, and in which the catchup control means for each control unit includes means for signalling to the yard operator the occurrence and location of a catchup.
 11. An electrical control system for route switching in a railroad classification yard or the like including a plurality of track switches interconnected in a given pattern for directing vehicles along a series of routes diverging from a first track switch downstream to a given number of different destinaTion tracks, said control system comprising: a corresponding plurality of track switch control units, one for controlling each track switch, each control unit including a track switch storage unit, comprising at least one solid-state storage device, having a storage capacity sufficient to store a route command, encoded in accordance with a given destination code, to identify a route through its associated track switch and all other track switches traversed to reach any destination downstream of the associated track switch, each track switch control unit further comprising track switch position sensing means for determining the present position of the associated track switch; a limited number of preliminary storage units each having a storage capacity sufficient to store a complete route command for any destination in the yard; data transmission means interconnecting said track switch storage units with each other in a pattern corresponding to said given pattern and further interconnecting said preliminary storage units in a series, the last storage unit in the series being the first track switch storage unit; encoding means for entering complete route commands one at a time, in the first preliminary storage unit; clearing means, in each track switch storage unit, for automatically clearing that track switch storage unit of a route command stored therein whenever a vehicle enters the track switch with which the storage unit is associated; and input control means, in each downstream track switch storage unit, comprising an AND gate, for conditioning said storage unit to record a new route command only in response to the following combination of input control signals: A. a route stored signal from the adjacent upstream track switch storage unit; B. a signal from a storage device in the adjacent upstream track switch storage unit indicating that the route command stored therein calls for the downstream storage unit; and C. a signal from the track switch position sensing means of the adjacent upstream track switch control unit indicating the adjacent upstream track switch has been thrown to a position leading to the downstream track switch; said data transmission means operating to record any route command stored in an upstream storage unit in the adjacent downstream track switch storage unit when said downstream track switch storage unit is cleared.
 12. A route-switching control system according to claim 11, in which each track switch control unit further comprises a track switch actuator for throwing the associated track switch, and track switch throw control means for initiating operation of said track switch actuator to throw the associated track switch in response to entry of a route command in the storage unit of the track switch control unit that requires positioning of the track switch in a position other than its present position.
 13. A route-switching control system according to claim 11, in which each track switch storage unit includes a bistable route stored circuit for developing a route stored signal whenever a route command has been recorded in that storage unit and has not been cleared by said clearing means, and in which said input control means includes inhibiting means for precluding recording of a new route command in said storage device in response to either of the following signals: A. the route stored signal from the same track switch storage unit indicating a route command is already stored therein; and B. a clearing signal from the clearing means, in the same track switch control unit, indicating a clearing operation is taking place. 